Contrary to the ski or a monoski, the snowboard is used asymmetrically, the user having neither his body nor his feet directed along the longitudinal axis of the board, but placed markedly obliquely with respect thereto. The surfer's body is placed oblique with respect to his board with either the right foot to the rear and the left foot in front, for persons with right directing foot ("regular foot") or, for persons with left directing foot ("goofy foot"), the left foot to the rear and the right foot at the front. The spaced apart relationship of the feet depends on the user's morphology and essentially on his size. The tips of the feet are more or less turned towards the front of the snowboard, this orientation being indicated by an angle measured from the perpendicular to the longitudinal axis of the snowboard. This orientation may generally vary, for the rear foot, between 0 and about 40 degrees and, for the front foot, between 10 and 45 degrees, the position preferred at the present time by numerous high-level surfers being the so-called intermediate position:
rear foot: angle of orientation included between 10 and 15 degrees, PA1 front foot: angle of orientation included between 30 and 45 degrees. PA1 "Free snowboarding" (or "free ride") which combines passages on marked runs and off-piste, PA1 "Figures" (or "free style") on especially arranged runs, including parts in relief allowing jumps to be made. PA1 by a gliding surface composed of a sole for gliding bordered by metal edges, PA1 by a lower reinforcing layer, either fibrous or metallic, PA1 by a core, PA1 by an upper reinforcing layer, either fibrous or metallic, PA1 by a protecting and decoration-supporting foil, made either in the form of a shell and therefore constituting the top and sides of the board, or existing solely on the upper face of the board and therefore, in that case, in abutment on protecting elements bordering the core and called sidewalls.
As the case may be, the surfer's body is oblique with respect to the snowboard and to the direction of his displacement. Bends are taken either by leaning the body forwards, towards the tips of the foot (or, more simply, "front-side"), or by leaning the body backwards, towards the heels (or "back-side"). The center of gravity of the surfer then moves along an axis whose orientation is substantially the bisecting line of the angle formed by his two feet.
Originally, the snowboard was mainly intended to be used off-piste in answer to a demand particularly centered on freedom and therefore the search for a new way to glide in wide open spaces, away from the crowds on the runs.
Later, this practice was divided into two specialties:
Finally, like Alpine skiing, certain practitioners have felt the need to match themselves against one another in competitions on slalom or downhill runs. This activity will be classified overall as "Alpine snowboarding".
This craze for snowboarding is also affecting persons other than the very young, with the result that it is also becoming necessary to provide, on the one hand, snowboards for women, presenting qualities of lightness and comfort, and, on the other hand, "general public" snowboards presenting qualities of comfort without being too detrimental to efficiency and lightness.
A snowboard is conventionally constituted, from bottom to top:
More particularly, for producing a snowboard, the mechanical characteristics of the core constituting the internal part must be adapted, due to the width thereof which is much larger than is necessary for producing a ski.
These particular characteristics are obtained at the present time either by dimensional values, by appropriate internal reinforcements, or by the nature of the components, particularly concerning the core. It may be noted, for example, that:
A core made of wood is very tonic, heavy, slightly vibrating, and of relatively low cost price. It improves the mechanical characteristics of stiffness (vivacity, nervosity), of resistance to deformation, of resistance to tear of the screws maintaining the shoe bindings, as well as the characteristics of adhesion.
Compared to a core made of wood, a core made of synthetic foam is lighter, less tonic, much dampened, but slightly more expensive if it is question of a fiber-reinforced polyurethane foam; much less expensive due to its easy use and completely inert if it is question of a polyurethane foam; and even more dampening but much more expensive if it is question of an acrylic foam.
The invention makes it possible to respond, by a very particular constitution of the core of snowboard, therefore forming the subject matter of the invention, to all the specific uses of this board, and consequently to be able to produce either an "Alpine" snowboard for runs, a "free style" snowboard for acrobatics, or a multi-use "free ride" board.